Precise fabrication of surface-reconstructed LaMnO₃ perovskite with enhanced catalytic performance in CH₄ oxidation

In this study, MnO_x/LaMnO₃ catalyst (LMO) was successfully synthesized through a selectively etched method, wherein MnO_x was in-situ formed on the surface of LaMnO₃. The modified LMO catalysts possessed the large specific surface area, high molar ratios of Mn⁴⁺/(Mn⁴⁺+Mn³⁺), and outstanding low-temperature reducibility. Moreover, the more efficient electron transfer from Mn³⁺/Mn⁴⁺ redox cycles and O₂ ⇔ O_L due to the generation of oxygen defects contributed to the strong interaction between MnO_x and LaMnO₃. Among all LMO catalysts, the LMO-4 (etched 40 min) catalyst exhibited the excellent activity (T₉₀ at 448 °C), stability and optimum endurability in methane catalytic combustion (5 vol% water) during the steady state of 100 h, which could be greatly assigned to its larger specific surface area, superior low temperature reducibility, the highest molar ratio Mn⁴⁺ and better oxygen mobility. The lowest apparent activation energy (E_a) of LMO-4 catalyst (61.8 kJ/mol) was in good accordance with its optimum catalytic activity for methane combustion.